Research and Development of Novel Refractory of MgO Doped with ZrO2 Nanoparticles for Copper Slag Resistance

This study investigates the corrosion mechanism on 100 wt.% MgO and 95 wt.% MgO with 5 wt.% nano-ZrO2 ceramic composites. First, MgO powder and powder mixtures (MgO + nano ZrO2) were uniaxially and isostatically pressed; then, they were sintered at 1650 °C. Corrosion by copper slag was studied in sintered samples. Physical properties, microstructure, and penetration of the slag in the refractory were studied. Results reveal that ZrO2 nanoparticles enhanced the samples’ densification, promoting grain growth due to diffusion of vacancies during the sintering process. Additionally, magnesia bricks were severely corroded, if compared with those doped with nano-ZrO2, mainly due to the dissolution of MgO grains during the chemical attack by copper slag.

Study of the corrosion resistance on nano-ZrO2 doped MgO ceramic composites by copper slag.

This study investigated the corrosion mechanism on 100 wt. % MgO and 95 wt. % MgO with 5 wt. % nano-ZrO2 ceramic composites. First, MgO powder and powder mixtures (MgO + nano ZrO2) were uniaxially and isostatically pressed and, then, they were sintered at 1650 °C. Corrosion by copper slag was studied with sintered samples. Physical properties, microstructure and penetration of the slag in the refractory were studied. Results reveal that ZrO2 nanoparticles enhanced the densification of the samples, promoting grain growth due to diffusion of vacancies during sintering process. Additionally, magnesia bricks were severely corroded, if compared with those doped with nano-ZrO2, due to the dissolution of MgO grains during the chemical attack by copper slag.

Аномалии упругих и неупругих свойств наногранулированных композиционных материалов Co-=SUB=-x-=/SUB=-(CaF-=SUB=-2-=/SUB=-)-=SUB=-100-x-=/SUB=-

Elastic ( G ) and inelastic ( Q ^–1) properties of the Co_ x (CaF_2)_100 –_ x ( x = 41–84 at %) nanocomposites fabricated with the aid of ion-beam sputtering are studied in a temperature interval of 170–750 K. Maximum internal friction related to hopping of Co atoms inside metal granules is revealed at a temperature of 227 K. It is shown that the maxima increase with increasing concentration of metal phase. A noticeable increase in dependence Q ^–1( T ) at a temperature of greater than 675 K is caused by diffusion of vacancies in the Co granules under geometrical confinements.

Рост ограненных пор в кристалле по механизму Бартона--Кабреры--Франка

The growth of a faceted pore in a crystal via Burton-Cabrera-Frank mechanism under tensile load is considered. The growth is due to diffusion of vacancies containing in the crystal, towards terraces and steps on the pore surface. Expressions for the rate of advance of a single step and a group of parallel steps are found as well as the expression for the dependence of the normal growth rate of a pore by a spiral mechanism on the applied tensile load. It is shown that in a certain range of small tensile loads, the pore growth rate may have a quadratic dependence on the load, whereas for large loads this dependence is linear.